wjmdes

Changing Roof Pitch Changes Bearing Height

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I have had this issue before, and I do not understand why this happens.  I manually place a roof plane on a wall and Chief uses the settings under "Build Roof" and everything is fine.  If I then decide to change the pitch of the roof, it apparently pivots around the baseline, not the bearing point where rafters sit. This causes the exterior wall height to change which is incorrect.

 

Is there way to fix this?  In my opinion, the "baseline" should be on the inside of the stud at the rough ceiling height.

 

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I have also just noticed that if later I need to change the rafter depths, it lowers the wall height, it does not move the roof up.  The walls heights should be a constant.

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7 minutes ago, wjmdes said:

it apparently pivots around the baseline

 

That's the default. You can lock the fascia, shadow boards etc.

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7 minutes ago, solver said:

 

That's the default. You can lock the fascia, shadow boards etc.

Locking the fascia or shadow board will also change the wall height.

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That's a huge roof pitch change. Generally when I make a big roof pitch change and even change the framing size, I delete that roof plan, make correct changes and redraw the roof plane. Reconnect all necessary roof planes. Most of my roofs are done manually.

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I'm not the sharpest (CAX11) pencil in the box, but if you set your default ceiling height, correctly, and if you change the pitch of the roof by selecting the specific wall, (not by the roof plane itself) as Glenn Woodward taught me, the ceiling height should remain as you've set it?  Am I wrong? This is one he may chime in on once he gets out of bed! :D

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2 minutes ago, tommy1 said:

Generally when I make a big roof pitch change and even change the framing size, I delete that roof plan, make correct changes and redraw the roof plane.

 

Me too.

 

I'll use auto roofs too.

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7 minutes ago, Evolution said:

nd if you change the pitch of the roof by selecting the specific wall, (not by the roof plane itself)

I tried that and that must work for auto roofs as it did not affect anything when I changed it.

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8 minutes ago, solver said:

Me too.

 

I'll use auto roofs too.

Apparently I will need to take the long road.  I do manual roofs also and in some cases such as this house, I have to create a substantial addition on the back and get all the water to drain off and also make it look good from the street and also make the historic commission happy.  So I end up changing roof pitches quite a bit sometimes.  This explains why when I get near the end of putting the plans together and start generating sections they are always wrong.

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If you lock the "baseline"...yes, the rafter will pivot around this point.  Of course...you need to know where the "baseline" is.  It's probably not where you think it is.  

 

It's here...see diagram below;

2019-11-21_15-37-17.thumb.png.e71fa596e155f3b468e5b5d3283e08a3.png

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5 minutes ago, SNestor said:

If you lock the "baseline"...yes, the rafter will pivot around this point.  Of course...you need to know where the "baseline" is.  It's probably not where you think it is.  

 

It's here...see diagram below;

2019-11-21_15-37-17.thumb.png.e71fa596e155f3b468e5b5d3283e08a3.png

 

Yep, that is where it is, the problem is that if you have built a complex roof manually and the client wants to go to a higher pitch, you have to start ALL OVER or it will be incorrect.

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And..that is why I do auto roofs whenever I can - you get direct feedback of any roof changes while editing the plan.

Why put yourself through the torture of manual roofs when there may be an easier and more accurate way.

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3 hours ago, wjmdes said:

 

Yep, that is where it is, the problem is that if you have built a complex roof manually and the client wants to go to a higher pitch, you have to start ALL OVER or it will be incorrect.

 

No...you can select each roof plane with the same pitch in plan view...or in 3D view.  Then, open the edit dialogue, click "lock pitch"...then change the "baseline" height the amount you want to raise or lower them.  It will raise or lower the roof planes.  No need to start over.

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18 minutes ago, SNestor said:

No...you can select each roof plane with the same pitch in plan view...or in 3D view.  Then, open the edit dialogue, click "lock pitch"...then change the "baseline" height the amount you want to raise or lower them.  It will raise or lower the roof planes.  No need to start over.

Correct, but then you need to determine the vertical distance the roof needs to be raised or lowered.  Not a big deal, just a pain.  Not sure who came up with the idea of where Chief has put the baseline, but the 100% most logical place would be on the inside of the stud wall at the top of the double top plate.  That point generally will not move when a pitch is changed or if a larger rafter is used.

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Many roofs are done with trusses.  It is common to have an energy heel of around 14".  Locking the baseline will keep the energy heel the same.

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37 minutes ago, wjmdes said:

Correct, but then you need to determine the vertical distance the roof needs to be raised or lowered.  Not a big deal, just a pain.  Not sure who came up with the idea of where Chief has put the baseline, but the 100% most logical place would be on the inside of the stud wall at the top of the double top plate.  That point generally will not move when a pitch is changed or if a larger rafter is used.

 

Uh...that's what I thought at first but...if you give this some thought it's not true.  You are assuming all rafters will sit on the double top plate at the top of the wall...but, what if you raise the roof so that it is actually sitting on top of the plate of an "attic wall"?  Which happens all the time.  Also...how thick is the wall...what depth have you set the "seat cut" to...and, what is the roof pitch and rafter depth.  There are a lot of variables.

 

Chief has to be able to place a polyline box (the rafter) at the correct pitch and I think the only consistent point to "spring" the box from is the "baseline" point I've shown above.  The software will always know where this point is.  Yes...it's not "logical" to those of us that designed roofs for years with paper and pencil.  I'm right there with you...but, you have to figure out how the software works and then make it work for you.

 

I think you may want to create a cad detail.  Draw your roof on top of the wall...at the pitch you want..or create multiple sections if you are using different roof pitches...and calculate the roof baseline elevation in this detail...then transfer this info to your roof building dialogue.  

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1 hour ago, SNestor said:

Uh...that's what I thought at first but...if you give this some thought it's not true.

Yes,....but for most situations, it is the case.  Either way, I started a spreadsheet that will give me baseline above my entered top of wall height, and stud size and rafter size.  Four years of calculus and I only use trig!  I appreciate you making me think.

 

And at the end of the day, being a little off will never be noticed when they build it, but it bugs me.

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1 hour ago, wjmdes said:

And at the end of the day, being a little off will never be noticed when they build it, but it bugs me.

Welcome to my world! I constantly fight "myself" over this. I spend far more time than I should on these OCD areas when some of them just don't matter that much. :)

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2 hours ago, wjmdes said:

Yes,....but for most situations, it is the case.  Either way, I started a spreadsheet that will give me baseline above my entered top of wall height, and stud size and rafter size.  Four years of calculus and I only use trig!  I appreciate you making me think.

 

And at the end of the day, being a little off will never be noticed when they build it, but it bugs me.

 

How accurate were we in paper/pencil days?  Get it close...draw a line and use a rich text box to state the "plate height".  Then...move on to the next problem.  I don't think we get paid enough to spend all day trying to get Chief to build a rafter within a sixteenth of an inch where it's "supposed" to be....

 

Maybe I'm alone on this?  

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I continue to believe Chief should just provide a toggle to allow the baseline to be located at either the inside bottom or the outside top. For rafter framing auto roofs would automatically place the baseline at inside bottom.  For truss framing, auto roofs would automatically place the baseline at outside top.  Outside auto build, the toggle would be on a plane by plane basis and could be toggled at will.  

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9 hours ago, SNestor said:

Maybe I'm alone on this?

No. I am with you! I never want to justify "sloppy" work, but some things just aren't as important as we often make them. :)

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9 hours ago, SNestor said:

Get it close...draw a line and use a rich text box to state the "plate height".

This becomes an issue when I am doing a porch or covered deck addition.  The entire existing house is a 12:12 pitch and then when I get around to playing with the new roof, I draw it in using the previous settings and then change the pitch to maybe a 2:12 pitch to avoid 2nd story window sills.  Now we are talking inches not sixteenths.  However, this whole thread and other people's input, I now understand better how this works.  Messed around with it last night and a real quick fix t get the rafter sitting back where it needs to be.

 

Now that I know you can display a baseline, can somebody explain to me a situation where you would move it....

 

 

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32 minutes ago, wjmdes said:

This becomes an issue when I am doing a porch or covered deck addition. 

 

In this situation, I would draw in a roof plane, set the ridge height as required, then set the fascia height -- maybe it needs to match the existing, or maybe it needs to just look good etc. Only then would I consider the pitch. 

 

45 minutes ago, wjmdes said:

Now that I know you can display a baseline, can somebody explain to me a situation where you would move it....

 

After moving a wall under an existing roof, selecting the baseline and using point-to-point move is a quick way to move the roof plane back into position over the wall.

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22 hours ago, wjmdes said:

Yes,....but for most situations, it is the case.  Either way, I started a spreadsheet that will give me baseline above my entered top of wall height, and stud size and rafter size.  Four years of calculus and I only use trig!  I appreciate you making me think.

 

And at the end of the day, being a little off will never be noticed when they build it, but it bugs me.

 

Not a spreadsheet but here is a Cheat Sheet Curt Posted a few years ago....... the VRD is now the VSD in X11

 

Curt's Energy Heel Info.pdf

 

This topic had quite the discussion in the Suggestion forum a few months ago too :

 

https://chieftalk.chiefarchitect.com/topic/21163-provide-a-top-plate-lock-in-the-roof-plane-dbx/

 

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